"xanthine"@en-us . . "114257289"@en-us . "xanthine"^^ . . "0"^^ . . "crystalline oxidation product of the metabolism of nucleoproteins; precursor of uric acid; found in many organs and in urine"@en-us . "crystalline oxidation product of the metabolism of nucleoproteins; precursor of uric acid; found in many organs and in urine"@en-us . . . "115113050"^^ . . . . "0"^^ . . "15113050-n"^^ .